Process for the production of combinations of rubber and paper and product obtained thereby



Patented Apr. 29, 3.93%

STATES PATENT caries REED P..BOSE, OF JACKSON HEIGHTS, AND HAROLD E.CUDE, OF FLORAL PARK, NEW

YORK, ASSIGNORS T GENERAL RUBBER COMPANY, OF NEW YORK, N. Y., A COE-IPORATION OF NEW JERSEY PROCESS FOR THE PRODUCTION OF COMBINATIONS OFRUBBER AND PAPER- AND PRODUCT OBTAINED THEREBY No Drawing.

This invention relates to processes for the production of combinationsof paper, rubher and other ingredients adapted to impart specialproperties to the paper. The invention is also concerned with methodsfor depositing such paper modifying materials from a dispersion upon apaper making pulp of any sort. The invention also includes within itsscope the production of paper having special properties of waterresistance,

grease resistance, or high electrical insulating value, or of several ofthese and other properties conferred upon paper by the methods andmaterials herein recited.

In the manufacture of paper for special purposes, where the paper isrequired to be water resistant, grease-proof, or must possess highinsulating value, it has been the practice to incorporate variousingredients with the paper prior to its manufacure into sheets orsubsequently thereto as a coating. These special papers are not new inthe art. But when rubber is incorporated with the paper, as for exampleby the addition of rubber latex to the paper pulp, the value of theingredients usually added to increase'water resistance, etc., becomesgreatly enhanced and the properties of the papers thus prepared arefrequently entirely different than where the rubher is not used.

The primary object of the present invention is to provide a method forincorporating various ingredients with rubber and paper stock. Anotherobject is to provide a method for adding such ingredients to paper fromtheir dispersions, suspensions, or emulsions. A further object is toincrease the retentive power of paper with respect to the so-calledApplication filed October 9, 1925.

Serial No. 61,571.

scribed as consisting in forming a dispersion of a desired papermodifying ingredient, combining the dispersion with a paper-making pulpin the presence of a dispersion of rubber, and depositing the desiredingredient together with the rubber upon the pulp and subsequentlyforming the pulp into sheets.

The addition of rubber to paper, particularly the addition of rubberderived from latex, increases the retentive power of paper for finelydivided solids, such as clays, talc, and the like, known to the industryas loading'materials. The increased retention may be as much as 50%higher when rubber is present on the paper fibre than where rubber isnot incorporated. Various other materials may beadded similarly to apaper making pulp, thereby modifying the properties of the paper withrespect to moisture, grease, adhesion, etc. According to the pres entinvention, various modifying ingredients may be added to the pulp, inthe form of dispersions, to confer special properties upon the paper.Such ingredients are tars, pitches (such as the hard wood pitches),resins (such as cumar), phenol-aldehyde condensation products,resinates, waxes, gums, ester gums, drying oils, non-drying oils. Theyare added in the form of dispersions, suspensions, or

. emulsions, and it is preferable to prepare the dispersions in such a.way that they will be coagulated by means of the paper-makers" alum orwhatever coagulant is to be used for the particular paper being made.

As one example of the invention, an emulsion or suspension of aluminumresinate, is prepared by grinding the material in a ball mill or coloidmill or other suitable ap aratus with a solution containing 5-10% 0ammonia. The addition of an emulsifying or peptizing agent such ascasein, glue, one of the modified starches, soaps, such as the oleates,stearates or palmitates of sodium, potassium or ammonium acts to hastenthe dispersion of the resinat-e and at the same time tends to stabilizethe resulting dispersion.

In applying this material to the manufacture of a waterproof paper,paper pulp is prepared for the formation of a sheet on any standard typeof paper machine by beating beater roll is raised off the bed plate andrubber latex is added. The alkali and protective colloid are added tothe suspension of paper pulp in order to avoid any possible coagulationof the latex when added to the pulp. Diiferentbatches of latex may varyinsensitivity due to partial destruction of the proteinous protectivecolloid surrounding the latex particles. As a result, when the .latex isdiluted, if its protective colloid has been partially removed ordestroyed, it is in an unstable condition. Another condition which maytend to cause coagulation of the latex is that in some cases the pulpmay be acid, and still another condition liable to cause this trouble isthat the water may contain suspended finely divided lime compounds. Bythe addition of the alkali and the protective colloid to the pulp, anyacidity of the pulp suspension is neutralized and the individualparticles of pulp and any suspended calcium compounds are coated with aprotective colloid. Hence, when the latex is added, all risk ofcoagulation is obviated. The beater roll is then made to serve as ameans for agitating the pulp and thoroughly mixing the latextherewith.After the latex has become mixed with the pulp, the dispersion ofaluminum resinate is then added to the contents of the beater in aquantity sufficient to give, say 510% of dry aluminum resinate on theweight of the dry fibre in the beater. It is obvious that the order ofadding the latex and aluminum resinate dispersion may 'be reversed, orthey may be added together. The rubber may then be agglomerated by theaddition of an insuflicient amount of coagulant to cause completecoagulation, meanwhile continuing the agitation. When about of thequantity of coagulant necessary to accomplish complete cogulation hasbeen added, the latex will have become agglomerated, but not coagulatedupon the pulp. The addition is then stopped for a short time while theagitation is continued. This serves to distribute the agglomeratedrubber and the aluminum resinate uniformly upon the paper fibre, and therubber Will be found adhering to the fibre. The remainder of thecoagulation solution is then added to complete the coagulation and toimpart an acid-reaction to the contents of the beater. The paper fibreobtained by this treatment is then formed into a finished sheet by anystandard paper making process. The finished sheet will be found tocontain approximately 7 0% of the aluminum resinate added to the beater,and the sheet is substantially waterproof. The degree of resistance towater may be varied within Wide limits by the use of varying quantitiesof the aluminum resinate.

The above result may be also obtained by the formation of aluminumresinate from the reaction between the ordinary rosin size used in papermaking and paper makers alum. Howeyer it has been found thatconsiderable difiiculty may be experienced in the clogging of the wiresand felts on the machine when high percentages (over 4%) of thismaterial are used. This sticking-can be entirely eliminated by the useof aluminum resinate prepared as described above.

Another illustration of the invention is in the production of papershaving high insulating properties by the addition of an insulatingmaterial to the paper. Resinous products such as cumar resins, phenolaldehyde condensation products, pitches such as hard wood pitches, maybe added to paper according to the example given above. These materialscan be dispersed in a carrier liquid, preferably water, and they maybeused in exactly the same manner as the aluminum resinate dispersiondescribed above. Loading materials such as clays, talc, etc., may beadded as dry powders or as dispersions, and the finished paper will befound capable of retaining considerably greater quantities of thesematerials than is possible for ordinary. paper to retain.

- Other types of waterproof papers may be prepared by the addition ofthe fatty acid salts ofthe alkaline earth metals or of the metals of thealuminum group. Papers of the general type known as wax papers may beprepared according to this invention by adding emulsions or dispersionsof waxes such as those of the paraffin group, saponifiable waxes, suchas Japan wax, carnauba, etc. The properties imparted by these waxes. andother materials are eminently more desirable in the presence of adispersion of rubber than without the rubber, and fre-' quently theproperties are different in the finished sheet. Varying degrees offlexibility may be obtainedin the papers by using more than oneingredient or by using a specially adapted ingredient such as a lowsoftening point tar or an oil. Pliable papers having the property ofhardening after a period of time may be prepared by including a dryingoil in the added dispers'i'o'ii The present invention oflers methods forproducing papers which are entirely imper- "VIOUS to moisture and gases.These products pitches, or the waxes mentioned above have, after hotcalendering, a glossy, impervious surface. This may probably be due tothe fact that the materials sweat or bloom to the surface of a sheetwhen passing through the hot calender, and thus form films on thesurface of the paper. It is preferable, but not absolutely necessary, insome cases such as electrical insulating paper to calender the paper ina vacuum, in which instance the re sultant sheet will containsubstantially no air or gas or moisture Within its structure, and afterhot calendering the film which is formed on the surface prevents anyreabsorption of air, gases or moisture by the paper.

The expression paper modifying material in the specification and claimsis used in a generic sense as descriptive of the materials employed inthe paper industry to impart specific properties to the paper, such aswater resistance, grease resistance, high electrical insulating value,opacity. stiffness, flexibility, and other special properties whichordinary paper does not possess at all, or else to a limited degree, andthe expression therefore excludes the ordinary loading and sizmgingredients.

Having thus described our inventlon, what we claim and desire to protectby Letters Patent is:

1.'A process of manufacturing a waterproof paper which comprises beatingpaper making fibre, adding a protective colloid and an alkali thereto,mixing a dispersion of paper waterproofing material and a rubberdispersion with the beaten fibre, depositing the material and the rubberupon the fibre, and forming the treated fibre into a sheet.

2. A process of manufacturing a waterproof paper which comprises beatingpaper making fibre, adding a protective colloid and an alkalithereto,mixing a dispersion of waterproofing material embodying a resin and arubber dispersion with the beaten fibre in the presence of theprotective colloid, uniformly depositing the material and the rubberupon the fibre with the aid of a coagulating agent, and forming thetreated fibre into a sheet.

3. A process of manufacturinga waterproof. paper which comprises mixinga preformed dispersion of a water insoluble resin soap and rubber latexwith beaten paper fibre containing a protective colloid, depositing theresin soap and the rubber upon the paper making fibre, and forming thefibre into sheets. 7

4. A process of manufacturing a waterproof paper which comprises mixinga preorrned dispersion of a water insoluble metallic resinate withbeaten paper fibre containing a protective colloid and rubber latex,depositing the metallic resinate and the rubber upon the paper makingfibre, and forming the fibre into sheets.

5. A process of manufacturing a waterproof paper which comprises mixinga preformed dispersion of aluminum resinate with beaten paper fibrecontaining a protective colloid and rubber latex, depositing thealuminnm resinate and the rubber upon the paper making fibre, andforming the fibre into sheets.

6. A process of manufacturing a paper article which comprises, formingin the presence of a protective colloid a colloidal suspension of awater insoluble paper modifying ingredient exclusive of the usualfilling and sizing ingredients, mixing the suspe ion and a rubberdispersion with a suspension of paper pulp in the presence of aprotective colloid and an alkali, uniformly and firmly depositing thesuspended materials on the pulp by the addition of a coagulant, and

forming the pulp into an article.

7. A process of manufacturing a paper article which comprises beating apaper making fibre, adding a protective colloid and an alkali thereto,mixing in rubber latex, forming a colloidal suspension of a waterinsoluble paper modifying ingredient exclusive of the usual filling andsizing ingredients and adding said suspension to the latex and the pulpmixture, adding a coagulant and uniformly depositing the rubber andpaper modifying ingredient on the pulp, and forming the pulp into anarticle.

Signed at New York, New York, this 3rd day of October, 1925.

- REED P. ROSE. Signed at New York, day of September, 1925.

. HAROLD E. CUDE.

New York, this 15th

